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use conch_parser::ast::Arithmetic;
use conch_parser::ast::Arithmetic::*;
use env::VariableEnvironment;
use error::ExpansionError;
use eval::ArithEval;
use std::borrow::Borrow;
impl<T, E: ?Sized> ArithEval<E> for Arithmetic<T>
where T: Borrow<String> + Clone,
E: VariableEnvironment,
E::VarName: Borrow<String> + From<T>,
E::Var: Borrow<String> + From<String>,
{
fn eval(&self, env: &mut E) -> Result<isize, ExpansionError> {
let get_var = |env: &E, var: &T| {
env.var(var.borrow())
.and_then(|s| s.borrow().as_str().parse().ok())
.unwrap_or(0)
};
let ret = match *self {
Literal(lit) => lit,
Var(ref var) => get_var(env, var),
PostIncr(ref var) => {
let value = get_var(env, var);
env.set_var(var.clone().into(), (value + 1).to_string().into());
value
},
PostDecr(ref var) => {
let value = get_var(env, var);
env.set_var(var.clone().into(), (value - 1).to_string().into());
value
},
PreIncr(ref var) => {
let value = get_var(env, var) + 1;
env.set_var(var.clone().into(), value.to_string().into());
value
},
PreDecr(ref var) => {
let value = get_var(env, var) - 1;
env.set_var(var.clone().into(), value.to_string().into());
value
},
UnaryPlus(ref expr) => try!(expr.eval(env)).abs(),
UnaryMinus(ref expr) => -try!(expr.eval(env)),
BitwiseNot(ref expr) => try!(expr.eval(env)) ^ !0,
LogicalNot(ref expr) => if try!(expr.eval(env)) == 0 { 1 } else { 0 },
Less(ref left, ref right) => if try!(left.eval(env)) < try!(right.eval(env)) { 1 } else { 0 },
LessEq(ref left, ref right) => if try!(left.eval(env)) <= try!(right.eval(env)) { 1 } else { 0 },
Great(ref left, ref right) => if try!(left.eval(env)) > try!(right.eval(env)) { 1 } else { 0 },
GreatEq(ref left, ref right) => if try!(left.eval(env)) >= try!(right.eval(env)) { 1 } else { 0 },
Eq(ref left, ref right) => if try!(left.eval(env)) == try!(right.eval(env)) { 1 } else { 0 },
NotEq(ref left, ref right) => if try!(left.eval(env)) != try!(right.eval(env)) { 1 } else { 0 },
Pow(ref left, ref right) => {
let right = try!(right.eval(env));
if right.is_negative() {
return Err(ExpansionError::NegativeExponent);
} else {
try!(left.eval(env)).pow(right as u32)
}
},
Div(ref left, ref right) => {
let right = try!(right.eval(env));
if right == 0 {
return Err(ExpansionError::DivideByZero);
} else {
try!(left.eval(env)) / right
}
},
Modulo(ref left, ref right) => {
let right = try!(right.eval(env));
if right == 0 {
return Err(ExpansionError::DivideByZero);
} else {
try!(left.eval(env)) % right
}
},
Mult(ref left, ref right) => try!(left.eval(env)) * try!(right.eval(env)),
Add(ref left, ref right) => try!(left.eval(env)) + try!(right.eval(env)),
Sub(ref left, ref right) => try!(left.eval(env)) - try!(right.eval(env)),
ShiftLeft(ref left, ref right) => try!(left.eval(env)) << try!(right.eval(env)),
ShiftRight(ref left, ref right) => try!(left.eval(env)) >> try!(right.eval(env)),
BitwiseAnd(ref left, ref right) => try!(left.eval(env)) & try!(right.eval(env)),
BitwiseXor(ref left, ref right) => try!(left.eval(env)) ^ try!(right.eval(env)),
BitwiseOr(ref left, ref right) => try!(left.eval(env)) | try!(right.eval(env)),
LogicalAnd(ref left, ref right) => if try!(left.eval(env)) != 0 {
if try!(right.eval(env)) != 0 { 1 } else { 0 }
} else {
0
},
LogicalOr(ref left, ref right) => if try!(left.eval(env)) == 0 {
if try!(right.eval(env)) != 0 { 1 } else { 0 }
} else {
1
},
Ternary(ref guard, ref thn, ref els) => if try!(guard.eval(env)) != 0 {
try!(thn.eval(env))
} else {
try!(els.eval(env))
},
Assign(ref var, ref value) => {
let value = try!(value.eval(env));
env.set_var(var.clone().into(), value.to_string().into());
value
},
Sequence(ref exprs) => {
let mut last = 0;
for e in exprs.iter() {
last = try!(e.eval(env));
}
last
},
};
Ok(ret)
}
}